There is a requirement in aircraft position lights to limit light output in “overlap” areas of the photometric pattern. FIG. 2 shows an example of how position lights are supposed to appear under current flight rules. The position lights consist of an aviation red light 22 on the left (port) side and an aviation green light 24 on the right (starboard) and an aviation white taillight 26. This is done to prevent ambiguity in the light signal projected and to clarify the spatial orientation of the aircraft being observed.
Historically, lights have utilized a number of different baffle designs to accomplish the function of creating the light cut off for the overlap limit. One such design was to add additional parts to the light in order to block the light. Attaching additional parts to a light for the purpose of baffling creates extra costs due to extra components and the need to assemble the parts. Position accuracy may be impacted by tolerance stack up. The additional mechanical interfaces may cause vibration failures. An alternative method used, is to use opaque finishes on areas of lenses. Abrasion resistant opaque finishes for glass lenses are expensive, and baffle position in the finished part is not as consistent as desired. Finish adhesion is not always good. Opaque finishes on plastic lenses have presented similar difficulties.